A brake for an automotive falls into two categories: a drum brake and a disc brake.
The disc brake includes a disc and pads. The disc brake decelerates or stops a moving automotive by forcing the pads against the rotating disc. Braking action converts kinetic energy into heat. This requires the disc and pad to be made of a material which is lightweight, heat-resistant, erosion-resistant, wear-resistant, and high in strength and to have high coefficients of friction. In this respect, silicon-infiltrated, carbon fiber-reinforced carbon is a material suitable for producing the disc and pad.
The disc, made of silicon-infiltrated, carbon fiber-reinforced carbon, is hereinafter referred to as the “carbon-ceramic brake disc”
A process for producing a carbon-ceramic brake disc largely includes a first step of producing a porous, carbon-containing preform, a second step of densifying the porous, carbon-containing preform with a carbon matrix, a third step of forming the porous, carbon-containing preform into a green compact, a fourth step of infiltrating the green compact with silicon, and a fifth step of grinding the silicon-infiltrated green compact.
In the first step, two of the porous, carbon-containing performs are produced. The porous, carbon-containing preform is composed of a body and a friction layer.
In the second step, densification of the porous, carbon-containing preform with the carbon matrix is performed by chemical vapor infiltration or by using a liquid process.
In the third step, the two of the porous, carbon-containing preforms are combined into the green compact, with their respective bodies being opposite to each other.
In the fourth step, silicon is infiltrated into the green compact by the action of the capillary forces.
In the fifth step, the green compact is ground to a specified shape.
FIG. 1 is a block diagram illustrating a conventional method for producing a porous, carbon-containing preform.
In a first step P1 as shown in FIG. 1, a body is formed by superposing sheets of unidirectional fiber fabric on top of one another and bonding the sheets by a needle-punching operation. That is, at penetration of a needle, barbs of the needle carry with them some fibers from each sheet which the needle penetrates. As a result, the fibers carried by the barbs create vertical cross-linked bonds between the sheets of the unidirectional carbon fiber fabric, thereby forming the body.
In a second step P2, a friction layer is formed by stacking short carbon fibers and pressing stacked short carbon fibers at a specific pressure.
In a third step P3, the friction layer is bonded to the body with a binder such as a phenolic resin.
The conventional method for producing a porous, carbon-containing preform includes as many as three steps P1, P2, and P3 and provides a poor connection between the body and friction layer.